In mobile radio communication networks, such as cellular telephone systems, neighboring radio cells provide coverage of a geographical area to be serviced. Each cell has a base station (BS) operated on a set of radio channels. Over such radio channels communications are provided to and from mobile subscribers. A mobile switching center (MSC) controls calls between a group of base stations and the public switched telephone network (PSTN), integrated services digital network (ISDN), and one or more public land mobile radio networks (PLMN). The MSC performs functions such as call switching, routing, and charging.
All mobile communication networks provide the "basic call services" required for making and receiving calls in home and in foreign (hereinafter referred to as "visiting") mobile communication networks. In fact, known cellular systems like the Nordic Mobile Telephone System (NMT), the Total Access Communication System (TACS), the American Digital Cellular System (ADC), the Global System for Mobile Communication (GSM), and the Pacific Digital Cellular System (PDC) have all adopted standardized techniques for providing such basic services. Basic service includes calls to/from individual mobile subscribers and other services available to all mobile subscribers that do not require an individual service subscription.
Intelligent networks (IN) were developed to provide additional, more flexible services to supplement existing telephony services in the fixed telephony network. More recently, such IN-based services have also become necessary and/or desirable in mobile telecommunications networks. The term "standard supplementary services" is defined to include those supplementary mobile services which generally require an individual subscription and which are generally supported by most mobile communication networks (hence the term "standard"). Standard supplementary services include for example call waiting, call forwarding, and call barring. Standard supplementary subscriber services may be divided into two types: (1) those which modify or supplement the process of "originating" a call, and (2) those which modify or supplement the process of "terminating" a call. Examples of originating supplementary services include: barring of outgoing calls and closed user group. Examples of terminating supplementary services include: barring incoming calls, call forwarding, and call waiting.
A third category of services to which the present invention is particularly directed is network-specific supplementary mobile services. Network-specific services are generally offered to all mobile subscribers currently within that network. While the term "network-specific" is used for purposes of description, the term includes any location or service area that can offer services to mobile stations specifically in its area. In contrast to the standard supplementary services generally offered by many mobile communication networks, network-specific supplementary services are not standardized and are not generally offered by many mobile networks or are offered in different manners in different networks. This is because network-specific services are designed by individual network operators using intelligent network type tools, such as switch-based functions, or other means available in a particular network. Network-specific services help an operator distinguish itself from other operators by offering unique, specially-tailored services for mobiles being served by that operator's network.
The present invention is particularly concerned with providing such network-specific supplementary services to mobile stations even when those mobile stations are roaming outside of their home mobile communications network. Because the location of mobile stations may be continually changing, a database is generally used in each mobile communications network to keep track of particular mobile subscribers such as the home location register (HLR) used in the GSM cellular system. The HLR stores information for each mobile subscriber such as the mobile subscriber's (1) identification, (2) location--typically corresponding to the MSC currently serving the present location of the mobile subscriber, and (3) supplementary subscriber services.
In the example GSM mobile communications system, (adopted for purposes of explanation and not limitation), efforts have been made to develop Intelligent Network (IN) capabilities for mobile network operators in the Customized Applications for Mobile Network Enhanced Logic (CAMEL) standard published by the European Telecommunications Standards Institute (ETSI) as GSM Technical Specification 03.78. The goal of the CAMEL standardization process is to provide mobile network operators with the capability to quickly design and offer new and enhanced mobile network-specific services using intelligent network type tools, e.g., service logic building blocks, service databases, service "trigger" or "detection" points, etc. For example, a service control point (SCP) node stores and implements service logic invoked to provide supplementary services. A service switching point (SSP) node handles service detection and switching functions necessary to invoke services at the SCP. However, to reconcile the mobility of the subscribers in this IN framework, functions performed by the HLR, the SCP, and the MSC must be coordinated.
In order to provide IN-based, network-specific services to mobile subscribers, network-specific service subscription information, (referred to in the GSM CAMEL example as CAMEL Subscription Information (CSI)), must be stored in the subscriber record for each mobile subscriber. In CAMEL, such services to be invoked at the origination of a call from a mobile subscriber are indicated with originating-CSI (O-CSI), and CAMEL services to be invoked for a terminating call to a mobile subscriber are indicated with terminating-CSI (T-CSI). The CSI includes specific data including a service key, a gsmSCF address, and a default call handling procedure indication. The service key identifies service control function (SCF) service logic contained in an SCP node corresponding to a network-specific supplementary service. The SCF address identifies the specific SCP node where the corresponding service logic resides. The default call handling procedure indication is followed if something goes wrong in the process of invoking the network-specific supplementary service.
When a mobile subscriber registers at a visiting mobile communications network, that mobile subscriber's O-CSI must be sent from the HLR to the visiting mobile communications network as part of the typical mobile subscriber location update procedure. The O-CSI is stored at the visiting location register (VLR) database serving the area in which the mobile subscriber is currently located. Thereafter, when that mobile subscriber initiates or forwards a call, the visiting network MSC/VLR detects the O-CSI stored for that subscriber in the VLR. In effect, the CSI functions as a Detection Point (similar to an IN "trigger" point in fixed telephony networks) in the call processing which causes a transfer of control to the Service Control Point (SCP).
A drawback with the arrangement for O-CSI and T-CSI as defined in the evolving CAMEL standard is that the O-CSI and T-CSI must be provided on an individual subscriber basis. Thus, if a mobile network operator desires to provide mobile subscribers with one or more network-specific services, the network-specific supplementary service data, e.g., the O-CSI in a CAMEL-based system, must be stored in the HLR for each potential mobile subscriber that may be operating within that operator's network. This is true even though the network-specific supplementary service and service parameters may be exactly the same for all mobile subscribers.
In practice, this results in significant data processing overhead to ensure a network-specific service is available to all potential subscribers. For example, if there is a total of one million potential mobile subscribers that may use a network-specific supplementary service, one million subscriber records in HLRs must be accessed to store the same network-specific supplementary service information. While the storage of large amounts of data in HLRs is a significant task, the administering and updating of the information is also a daunting. Each time the mobile network operator desires to change the network-specific supplementary services, e.g., service enhancement, all one million HLR subscriber records must be changed.
It would seem that a solution for network-specific supplementary services might be to simply include them as a basic service. But this is not a viable or attractive option. To viably provide such services using IN-type tools like CAMEL, a subscription is required as a means to detect when to transfer control of a call over an IN node for delivery of the service. From a commercial viability, network operators want to be able to distinguish their network-specific services from the basic services all network operators provide.
It is an object of the present invention to overcome problems and drawbacks described above.
It is also an object of the invention to more efficiently store information for network-specific supplementary services for large numbers of mobile subscribers.
It is a further object to efficiently administer and update network-specific supplementary services for large numbers of mobile subscribers.
Yet another object of the invention is to achieve these efficiencies while preserving the creation and delivery of customized, supplementary mobile services in an IN-context like CAMEL.
The present invention achieves these and other objects. Basic mobile telephony services are provided to mobile communication units operating within home and visiting mobile communications networks. The home and visiting mobile networks each include one or more mobile switching nodes that direct calls to and from mobile communications units. A home network database stores subscriber records for mobile communication units subscribing to the basic telephony services from the home mobile communications network. In addition, the home network database stores information relating to a network-specific service being offered in the home or visiting network. Although the invention applies to network-specific services offered in both home and visiting networks, for purposes of illustration, the network-specific service is assumed to be provided in the visiting network. Subscriber records in the home database include a network-specific service flag. If that flag is set, the mobile communications unit corresponding to that subscriber record is to receive the network-specific service. Thereafter, when a roaming mobile communication unit registers with the visiting network, the network-specific service flag is checked. If the flag is set, the network-specific service information is copied from the home network database to the visiting network database associated with the visiting mobile switching node. The copied network-specific service information is then used at the visiting mobile switching node to provide the network-specific service when the mobile in the visiting network when appropriate.
In another embodiment, an intelligent service control node includes service logic for providing the network-specific service when the roaming mobile communications unit triggers the network-specific service while operating in the visiting network. An intelligent service switching function associated with the visiting mobile switching node detects when the roaming mobile communications unit "triggers" the network-specific service and sends a request to the service control node to invoke the network-specific service.
The network-specific service information is stored only once in the home network database for each of the visiting mobile switching nodes in a particular network that supports the specific service. Alternatively, the network-specific service information is stored only once in the home network database for a selected number series associated with several visiting mobile switching nodes that supports the network-specific service.
Accordingly, the present invention provides network-specific services to roaming mobile subscribers without having to store the detailed network specific service information in each potential subscriber's home database record. Instead, a flag set in each participating subscriber's home database record links that mobile subscriber to the network/location area specific service information so that it may be transferred when that subscriber is being serviced in that network or location area. This approach reduces considerably the amount of data that must be stored in the HLR and simplifies administration and updating of network-specific services.